Annie and Suzette. I just saw your post. Hope I'm not too late. Cattails, pussy willows and other woody plants must be dried using liquid glyceren and water. Mix the liquids half and half. Put enough of mixed liquid in tall container filling it half full. P.ulverize the stems(I use the smooth side of a wooden meat mallet)about 1 1/2 inches from the bottom. Leave in mixture for at least 2 weeks replacing it as needed. Dry stems and trim bottom to make arrangement. I don't know of any other method but I do know if you don't do this the tails will explode. I speak from experience when I tell you this. If you want to spray a sealer on them after just get one that is used for dried flowers from a craft store. Let me know how things turn out.
Phyllie